[0001] This invention relates to structured aqueous detergent compositions comprising modified
cellulose and surfactant.
BACKGROUND
[0002] Detergent compositions such as hair shampoos, hand cleansing liquids, bath foam and
shower gels typically comprise one or more surfactants to provide cleaning. Such detergent
compositions are often thickened to impart the desired rheology for their particular
applications. A structurant may be used (either internal or external). This can impart
higher levels of storage stability to the composition and it may provide it with enough
structure to be able to suspend included solids or gasses, such as perfume capsules
or air bubbles.
[0003] Structuring may be provided by using a higher level of surfactant than is needed
for cleaning. Such surfactant containing detergent compositions, especially compositions
comprising mixed surfactants, tend to be highly thixotropic, or even to gel, and this
can provide the desired thickening and/or structuring. By higher levels, we mean 7
to 25 percent total surfactant when 2 to 3 percent would suffice for cleaning duty.
[0004] Many biopolymers can form reversible gels in aqueous solution. Polysaccharides, which
form reversible gels and may be used as rheological additives include agar, carrageenan,
furcelleran, gellan and pectin. However, though technically useful these biopolymers
are more expensive than surfactants, so there is no incentive to remove surfactant
and to use these materials instead. The more effective structurants may also suffer
from being derived from materials, or are made using processes, that make them potentially
undesirable for inclusion in a product that contacts skin and may get into the eyes.
[0005] Cellulose is a plentiful, and consequently inexpensive, biopolymer. However, in its
unmodified form it is completely insoluble and cannot be dispersed into an aqueous
liquid composition to achieve a stable, thickened, product.
[0006] The prior art discloses modified celluloses and their use in detergent compositions.
[0007] Complete oxidation of cellulose makes it soluble, as described in
GB 1299646 and
GB 1330123. Formation of polycarboxylic acids from cellulose sources is taught to be desirable
in order to transform the cellulose into a detergency builder. Such modified cellulose
builders require intensive processing to oxidise them sufficiently. This makes them
more expensive than typical surfactants. In addition, highly oxidised cellulose tends
to depolymerise and this leads to loss of structuring capability when the modified
cellulose is used in aqueous systems.
[0008] In
US 543 7810 liquid detergent compositions are viscosity modified using oxidised polysaccharide
with an acid index value of 1 to 20. In its fully oxidised form, cellulose may be
converted to polyglucuronic acid, which, because of its high solubility, is unsuitable
as a structurant.
[0009] GB 709941 describes a process for the production of undecomposed cellulose oxidation products
and the use of such products and their salts in detergent formulations. Cellulose
based woody raw materials are selectively oxidised at the primary alcohol (C6) position
on the anhydroglucose units. This process appears to oxidise the cellulose as much
as possible. It also teaches to use low levels of the material when surfactant is
present. The benefit is said to be improved detergency, presumably due to the builder
effect of the oxidised cellulose. Builder materials are also taught in
US 4056400.
[0010] Like C6 oxidised cellulose, pectin has C6 acid groups. However, it differs from C6
partially oxidised cellulose because instead of residual primary alcohol groups it
has methylated acid groups. This that makes it soluble and it therefore behaves differently
in the presence of anionic or amphoteric surfactants.
[0011] Chitin can be modified to make anionic polymers by partially oxidising the primary
alcohols as taught in
US 6037460, especially examples 7, 8, 9 and 11 where it is used to thicken a detergent composition.
These chitin derivatives are very expensive and do not exhibit good structuring properties
with a wide range of surfactants.
[0012] Partially and selectively oxidising cellulose at the C6 position creates cellouronates
or cellouronic acids which are more water dispersible than cellulose but still relatively
insoluble. Similar modified celluloses have been used in wound dressings, but for
that purpose, the targeting of oxidation onto the C6 primary alcohols has not been
important. C6 acids are made in the well known carboxymethyl cellulose, but this has
an additional CH2 separating the acid group and the C6 carbon. Because of this, and
its high degree of oxidation, CMC is soluble.
[0013] Two recent patent publications refer to C6 oxidised modified cellulose material.
JP2006 241601 relates to pulp modification for paper making. Oxidation of the C6 groups to aldehydes
is said to give greater wet strength to the paper. In
JP2008 001728, the same inventor oxidises a variety of cellulose starting materials using the same
catalytic route and then by using very high shear dispersions obtains a gel of oxidised
cellulose nanofiber. No surfactant is used or added to the dispersion.
[0014] The formulator would like to have an alternative structurant for aqueous detergent
compositions that is safe to use, is cheaper than the surfactant it replaces, and
that can be used with a range of surfactants to allow the level of surfactant to be
lowered to that required for the cleaning duty, whilst maintaining the ability to
provide detergent compositions of the required rheological profile and clarity.
SUMMARY OF THE INVENTION
[0015] According to a first aspect of the present invention there is provided a structured
aqueous detergent composition comprising modified cellulose and surfactant characterised
in that the composition comprises:
- a) 0.2 to 10 wt %, preferably 0.4 to 7 wt%, anionic surfactant or zwitterionic surfactant
or mixtures thereof,
- b) 0.5 to 5 wt %, preferably 1 to 2 wt%, dispersed modified cellulose biopolymer,
wherein the modification consists of the cellulose having its C6 primary alcohols
oxidised to carboxyl moieties (acid/COOH-) on 10 to 70% of the glucose units and substantially
all the remainder of the C6 positions occupied by unmodified primary alcohols,
- c) 0 to 10 wt % non-surfactant electrolyte;
- d) 0 to 15 wt% other conventional detergent composition additives
- e) balance water
[0016] The low concentration of surfactant combined with the modified cellulose, yields
soft gels with pleasing sensory characteristics. This enables the formulator to replace
surfactant required for structuring (but not for cleaning) with relatively low concentrations
of low cost, partially oxidised, dispersed modified cellulose.
[0017] These reduced surfactant compositions, which nonetheless maintain a thick gel-like
consistency, allow suspension of sensory enhancers, such as capsules (including perfume
containing encaps), beads, or glitter, which disperse rapidly in water upon dilution.
[0018] Also, according to a second aspect of the invention, there is provided a process
to manufacture a structured aqueous detergent composition according to the first aspect,
the process comprising the steps of:
- (i) dispersing 0.5 to 5 wt % modified cellulose biopolymer in water under high shear
to hydrate it, wherein the modification consists of the cellulose having its C6 primary
alcohols oxidised to carboxyl moieties (acid/COOH-) on 10 to 70% of the glucose units
and substantially all the remainder of the C6 positions occupied by unmodified primary
alcohols,
- (ii) adding 0.2 to 10 wt % of a surfactant system consisting of anionic or zwitterionic
surfactant, or mixtures of such surfactants, to this aqueous dispersion,
- (iii) optionally also adding 0 to 10 wt % non-surfactant electrolyte consisting of
low molecular weight salt, and
- (iv) optionally mixing in up to 15 wt% 0 to 15 wt% other conventional detergent composition
additives to make a structured aqueous detergent composition.
[0019] The modified cellulose biopolymer (i) is a water insoluble, water dispersible modified
cellulose in which only a proportion of its C6 primary alcohol groups have been oxidised
to acid groups. Cellulose where all such alcohols have been oxidised is called polyuronic
acid or polyglucuronic acid. Such fully oxidised material is soluble in water. It
is unsuitable for use in the present invention for two reasons. Firstly, the cost
of the extra processing required to create more than 70% substitution of primary alcohols
by carboxylic acid groups makes it not cost effective as a replacement for surfactant
and second the highly oxidised material tends to include unwanted depolymerised cellulose,
which leads to a reduction of yield of insoluble dispersible structurant.
[0020] In this specification, a modified cellulose biopolymer is said to be water soluble,
if it leaves less than 10 wt% of its dry mass as undissolved residue when a 2g dry
sample is added to I litre of agitated demineralised water at 25°C.
[0021] Totally unoxidised (unmodified) cellulose is unable to function as a structurant.
Oxidising the cellulose to have at least 10 % of the primary alcohols converted to
carboxylic acids makes the cellulose dispersible in water and when mixed within the
surfactant system the resulting structured liquid or gel maintains the cellulose in
a dispersed state so it does not settle over time.
[0022] Once the high shear dispersion of the modified cellulose has taken place, the remaining
process steps can take place in a conventional stirred tank, at relatively low shear.
This allows the formulator to make a stock of aqueous dispersion of the modified cellulose,
preferably stabilised by the further addition of anionic or amphoteric surfactants
or mixtures thereof and possibly also stabilised by the addition of some non-surfactant
electrolyte, such as sodium chloride. Further ingredients of a detergent composition
can be added to this mixture when needed to enable easy late-stage variations in composition
before products are packaged.
[0023] The structured aqueous detergent compositions also have the desired advantage that
lower levels of surfactants can be used and that some co-surfactant could be omitted
entirely to simplify the formulation. It is also possible that surfactants or surfactant
combinations previously regarded as unsuitable for use in hand applied compositions,
like hair detergents, may now be suitable, due to their amounts being reduced.
[0024] The invention provides structured aqueous detergent compositions having a structurant
derived from entirely renewable, non-petrochemical resources; structured aqueous detergent
compositions having a reduction in surfactant with retention of structuring; structured
aqueous detergent compositions having pleasant sensory characteristics; structured
aqueous compositions capable of suspending visual and sensory particles stably for
at least as long as typical storage durations, and a biodegradable product at end
of use.
DETAILED DESCRIPTION OF THE INVENTION
The cellulose starting material
[0025] Several factors influence the choice of a suitable starting material.
[0026] More porous unmodified cellulosic material will oxidise more rapidly. Characterisation
of surface area or porosity is readily achieved by porosimetry or BET measurements.
In general, those starting materials that oxidise more rapidly due to their low crystallinity
and higher surface area and/or porosity, prove easier to disperse than those that
oxidise less rapidly.
[0027] The rate of oxidation is also affected by the dimensions of the particles of cellulose
starting material; the reduction in rate for longer (>500 micron) fibres is significant.
Fibres less than 500 microns long are therefore preferred for this reason and due
to the added difficulty in agitation of the longer fibres. While oxidation results
in significant gross particle size reduction, this does not compensate for decreased
fibril surface accessibility in the long fibres.
[0028] Celluloses that have not been previously subjected to acid hydrolysis are a preferred
starting material, due to reactivity, cost and resultant product dispersibility.
[0029] Relatively unrefined α-cellulose, for example filter aid fibres, provides one of
the most readily oxidised and dispersed sources of cellulose. An unexpected advantage
of the process of the invention is the ability to use unbleached starting materials
that might be regarded as unsuitable for structuring a clear liquid detergent composition.
This is because the oxidation process also serves to bleach coloured components, such
as lignin, in such unbleached cellulose starting materials.
Oxidation
[0030] Because of its known specificity for primary alcohol oxidation TEMPO (and related
nitroxy radical species) mediated oxidation of cellulose is preferred. The process
proceeds well without cooling, at relatively high weight % cellulose in the initial
suspension. Simple workup procedures afford clean material suitable for dispersion.
Such TEMPO mediated oxidation of cellulose is described in the published literature
and the skilled worker will be able as a matter of routine to adapt known methods
to achieve the oxidation required by this invention.
[0031] While aqueous NaOCI/TEMPO/NaBr is a highly preferred oxidation system. There are
a number of other systems available to the skilled worker, especially for large scale
production. Among such systems, there may be mentioned use of peracetic acid or monoperoxysulfate
salts (Oxone®) as the oxidant with 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl
(4-acetamido-TEMPO) as the radical transfer catalyst or mediator and sodium bromide
cocatalyst for the oxidation. Elimination of chlorine from the oxidation system is
environmentally desirable.
[0032] The use of 4-acetamido-TEMPO as radical transfer catalyst is also advantageous as,
although it has a higher molecular weight than TEMPO, it has significantly lower vapour
pressure reducing potential exposure hazards. Many other 4-substituted TEMPO analogues
exist, but many, such as 4-hydroxy-TEMPO exhibit poor stability. TEMPO on solid supports
or on soluble polymers may be used.
[0033] Electrochemical oxidation is a potentially clean means of effecting oxidation of
carbohydrate moieties, although mediation by a radical transfer catalyst (such as
TEMPO) is still required.
[0034] Laccase mediated oxidation, which also requires a radical transfer catalyst (e.g.
TEMPO) but replaces the oxidant with an enzyme, may advantageously be used.
[0035] Using the TEMPO system the degree of reproducibility of oxidation of cellulose from
the same source is good.
Degree of oxidation
[0036] Throughout this specification when we refer to the degree of oxidisation of the modified
cellulose we refer to the percentage glucose units oxidised to carboxylic acid as
measured by titration with sodium hydroxide. It is assumed that all oxidation takes
place at the primary alcohol positions. A reasonable assumption, given that primary
alcohol specific oxidation chemistry is employed. Furthermore it is assumed that all
oxidation leads to carboxylic acid formation.
[0037] Degree of polymerisation (DP) does not seem greatly to influence the performance
of the modified cellulose. The key thing is that the modified cellulose must remain
insoluble. During oxidation, there is some degradation of the cellulose allowing release
of polymer chains. It is particularly advantageous to keep this to a minimum in order
to increase the yield of the modified insoluble cellulose material suitable for structuring
applications. We have determined that above 70 % oxidisation, the yield is unacceptably
low and the processing costs become unacceptably high.
[0038] The degree of oxidation of the modified cellulose lies in the range 10 to 70%. As
the degree of oxidation increases, the amount of soluble material produced will rise
and this reduces the yield of insoluble structuring material, thus the higher degrees
of oxidation confer no real structuring benefits. For this reason, it is preferred
to restrict the degree of oxidation to 60%, or even 50% and the most preferred modified
materials have degrees of oxidation even lower than 40 or sometimes even lower than
30%.
[0039] To achieve a high enough dispersibility/solubility for the modified cellulose to
act as a structurant it must be oxidised to at least 10%. The exact amount of oxidation
required for a minimum effect will vary according to the starting material used. Preferably,
it is at least 15% oxidised and most preferably, at least 20% oxidised.
Dispersal of the modified cellulose,
[0040] At small scale, high energy sonication is the preferred method to give the high shear
necessary to achieve the aqueous dispersion of the modified cellulose. However, other
techniques are more suitable for large scale applications. These include the use of
a high speed and high shear stirrer, or a blender, or a homogeniser. Homogenisation
may achieve higher levels of dispersed material than are attainable via sonication.
[0041] When degrees of oxidation of less than 10% are used, the partially oxidised cellulose
proves too resistant to dispersion to produce a transparent or translucent mixture
and higher energy input is required. Provided the lower limit of 10% is exceeded,
those modified celluloses with a lesser degree of oxidation appear to provide greater
structuring capacity once dispersed. This is attributed to less degradation of the
material during oxidation and thus the existence of longer individual dispersed (not
dissolved) fibrils. This may be because the structure of the cellulose starting material
is partially retained, but the fibrils are rendered dispersible by the introduction
of negatively charged functional groups on the surface during oxidation.
[0042] Oxidised, dispersed cellulose is a largely insoluble polymer that occurs in the form
of well dispersed fibrils rather than isolated solvated polymer chains. The fibrils
have a large aspect ratio and are thin enough to provide almost transparent dispersions.
Carboxylate groups provide anionic surface charge, which results in a degree of repulsion
between fibrils, militating against their reassociation into larger structures. Addition
of acid to dispersions of oxidised cellulose results in separation of gelled material
while at pH between ca 5-9 fibrils may be maintained in a dispersed form as the COO-
salt of an appropriate counterion.
The surfactants
[0043] The total amount of surfactant (including any co-surfactant, and/or any emulsifier)
in the detergent compositions is from 0.2 to 10wt%, preferably from 0.4 to 7 wt%,
more preferably from 0.5 to 5% by total weight surfactant based on the total weight
of the composition.
Anionic surfactants
[0044] Although any of the anionic surfactants conventionally used or usable in personal
care (skin contact) compositions may be used, either alone or in combination, it is
preferable that surfactants having mildness to the skin and especially naturally derived
and processed surfactants are used at least for part of the total surfactant system.
[0045] Preferred anionic surfactants include sodium lauroyl sarcosinate, sodium lauroyl
lactylate, sodium cocoyl glutamate, disodium alkylpolyglucose sulfosuccinate / citrate,
sodium lauryl ether sulphate (1-3 EO).
[0046] Other examples of suitable anionic surfactants are the alkyl sulphates, alkyl ether
sulphates, alkaryl sulphonates, alkanoyl isethionates, alkyl succinates, alkyl sulphosuccinates,
alkyl ether sulphosuccinates, N-alkyl sarcosinates, alkyl phosphates, alkyl ether
phosphates, and alkyl ether carboxylic acids and salts thereof, especially their sodium,
magnesium, ammonium and mono-, di- and triethanolamine salts. The alkyl and acyl groups
generally contain from 8 to 18, preferably from 10 to 16 carbon atoms and may be unsaturated.
The alkyl ether sulphates, alkyl ether sulphosuccinates, alkyl ether phosphates and
alkyl ether carboxylic acids and salts thereof may contain from 1 to 20 ethylene oxide
or propylene oxide units per molecule.
[0047] Typical types of anionic surfactants for use in detergent compositions of the invention
include sodium oleyl succinate, ammonium lauryl sulphosuccinate, sodium lauryl sulphate,
sodium lauryl ether sulphate, sodium lauryl ether sulphosuccinate, ammonium lauryl
sulphate, ammonium lauryl ether sulphate, sodium dodecylbenzene sulphonate, triethanolamine
dodecylbenzene sulphonate, sodium cocoyl isethionate, sodium lauryl isethionate, lauryl
ether carboxylic acid and sodium N-lauryl sarcosinate.
[0048] Preferred anionic surfactants of these types are sodium lauryl sulphate, sodium lauryl
ether sulphate(n)EO, (where n is from 1 to 3), sodium lauryl ether sulphosuccinate(n)EO,
(where n is from 1 to 3), ammonium lauryl sulphate, ammonium lauryl ether sulphate(n)EO,
(where n is from 1 to 3), sodium cocoyl isethionate and lauryl ether carboxylic acid
(n) EO (where n is from 10 to 20).
[0049] Mixtures of any of the foregoing anionic surfactants may also be used.
[0050] The total amount of anionic surfactant in detergent compositions of the invention
generally ranges from 0.1 to 10%, preferably from 0.5 to 7%, more preferably from
1 to 5% by total weight anionic surfactant based on the total weight of the composition.
Amphoteric surfactants
[0051] Although any of the amphoteric surfactants conventionally used or usable in personal
care (skin contact) compositions may be used, either alone or in combination, it is
preferable that surfactants having mildness to the skin and especially naturally derived
and processed surfactants are used at least for part of the total surfactant system.
Thus, a preferred surfactant could be olivamidopropyl betaine, a natural analogue
of CAPB derived from olive feed stock. A preferred amphoteric surfactant is sodium
cocoamphoacetate. Amphoteric surfactants are also called zwitterionic surfactants.
[0052] Other examples of amphoteric surfactants include alkyl amine oxides, alkyl betaines,
alkyl amidopropyl betaines, alkyl sulphobetaines (sultaines), alkyl glycinates, alkyl
carboxyglycinates, alkyl amphoacetates, alkyl amphopropionates, alkylamphoglycinates,
alkyl amidopropyl hydroxysultaines, acyl taurates and acyl glutamates, wherein the
alkyl and acyl groups have from 8 to 19 carbon atoms. Typical amphoteric surfactants
for use in detergent compositions include lauryl amine oxide, cocodimethyl sulphopropyl
betaine, lauryl betaine, cocamidopropyl betaine and sodium cocoamphoacetate. A preferred
amphoteric surfactant is cocamidopropyl betaine.
[0053] Mixtures of any of the foregoing amphoteric surfactants may also be suitable. The
total amount of amphoteric surfactant in detergent compositions of the invention generally
ranges from 0.1 to 10%, preferably from 0.5 to 7%, more preferably from 1 to 5% by
total weight anionic surfactant based on the total weight of the composition.
[0054] Mixtures of anionic and amphoteric surfactants may be used, especially when it is
desired to combine the cleaning effect of the anionic surfactant with the foaming
power of the amphoteric surfactant.
Other surfactants
[0055] Nonionic surfactants may optionally be used as co-surfactants, together with the
essential anionic or amphoteric surfactants. Suitable nonionic surfactants include
biosurfactants, for example Sopholiance S, an amphiphilic sophorolipid biosurfactant.
Another type of suitable nonionic co-surfactant is sorbitan trioleate.
[0056] For example, representative nonionic surfactants that can be included in detergent
compositions of the invention include condensation products of aliphatic (C8 - C18)
primary or secondary linear or branched chain alcohols or phenols with alkylene oxides,
usually ethylene oxide and generally having from 6 to 30 ethylene oxide groups.
[0057] Other representative nonionic surfactants include mono- or di-alkyl alkanolamides.
Examples include coco mono- or di-ethanolamide and coco mono-isopropanolamide.
[0058] Further nonionic surfactants, which can be included in detergent compositions of
the invention, are the alkyl polyglycosides (APGs). Typically, the APG is one which
comprises an alkyl group connected (optionally via a bridging group) to a block of
one or more glycosyl groups. Preferred APGs are defined by the following formula:
RO-(G)
n
wherein R is a branched or straight chain alkyl group, which may be saturated or unsaturated,
and G is a saccharide group.
R may represent a mean alkyl chain length of from about C5 to about C20. Preferably,
R represents a mean alkyl chain length of from about C8 to about C12. Most preferably,
the value of R lies between about 9.5 and about 10.5. G may be selected from C5 or
C6 monosaccharide residues, and is preferably a glucoside. G may be selected from
the group comprising glucose, xylose, lactose, fructose, mannose and derivatives thereof.
Preferably, G is glucose.
[0059] The degree of polymerisation, n, may have a value of from about 1 to about 10 or
more. Preferably, the value of n lies from about 1.1 to about 2. Most preferably the
value of n lies from about 1.3 to about 1.5.
[0060] Suitable alkyl polyglycosides for use in the invention are commercially available
and include for example those materials identified as Oramix NS10 ex Seppic; Plantaren
1200 and Plantaren 2000 ex Henkel.
[0061] Other sugar-derived nonionic surfactants which can be included in compositions of
the invention include the C10-C18 N-alkyl (C1-C6) polyhydroxy fatty acid amides, such
as the C12-C18 N-methyl glucamides, as described for example in
WO 92 06154 and
US 5 194 639, and the N-alkoxy polyhydroxy fatty acid amides, such as C10-C18 N-(3-methoxypropyl)
glucamide.
[0062] It is preferred to avoid use of cationic surfactants due to their charge being the
opposite of that of the modified cellulose. This causes unwanted interactions and
precipitation to occur.
Optional non-surfactant electrolyte
[0063] The non-surfactant electrolyte is optional; in combination with surfactant it does
not thicken as much as would be expected. This is not fully understood. The preferred
non-surfactant electrolyte is a water soluble inorganic or organic salt with a molecular
weight of less than 500. The electrolyte preferably has a monovalent cation, however
at low (less than 2wt%) levels salts with divalent cations, such as Calcium Chloride,
may be used.
[0064] Sodium Chloride is the preferred non-surfactant electrolyte.
Other conventional additives
[0065] Apart from a general need to avoid use of cationic polymers, that cause precipitation
with the anionic charged surfactants over a wide range of pH as used in personal care
products, all of the usual additives found in personal product compositions may be
added to the aqueous structured compositions comprising the surfactant and modified
cellulose according to the invention. The total amount of such additives will not
normally exceed 15wt%. The balance of the composition is water.
[0066] The detergent compositions may comprise a second suspending agent of the type conventionally
employed. The detergent compositions may comprise hair and/or skin conditioning agents.
[0067] Adding small amounts of perfume does not destabilise the structured aqueous detergent
compositions. Furthermore, perfume encapsulates, small beads, free emulsions and even
air bubbles stay suspended when dispersed at low shear in the structured aqueous detergent
compositions.
[0068] If too much water is added to the composition there is an eventual loss of structuring,
but provided the concentration of modified cellulose structurant and surfactant system
is kept above the lower limits of the invention the structuring is maintained. Advantageously
it is kept above a preferred lower limit of 1 wt% for each of the structurant and
the surfactant system.
[0069] The detergent compositions may contain other ingredients for enhancing performance
and/or consumer acceptability. Such ingredients include fragrance, dyes and pigments,
pH adjusting agents, pearlescers or opacifiers, viscosity modifiers, preservatives,
and natural hair nutrients such as botanicals, fruit extracts, sugar derivatives and
amino acids.
The invention will now be further described, with reference to the following non-limiting
examples.
Exemplary method for production of modified cellulose
[0070] The cellulose is suspended in water; the NaBr is added as a 0.5 M aqueous solution.
TEMPO catalyst is then added as a slightly acidified 0.03 M aqueous solution. Then
add NaOCl solution (assay 5-6.5 %) with the quantity of water adjusted to compensate
for the differing NaOCl quantities i.e. volume. Adjust to pH 10.5, maintain at this
pH by addition of NaOH during reaction under stirring at room temperature (nominally
25 °C).
Adjust pH to about 6 and isolate the modified cellulose by centrifuging. Wash with
water and recentrifuge. Finally, the pH may be adjusted to neutral using NaOH.
Modified celluloses # 1 to # 8
[0071] A number of samples of modified cellulose with differing degrees of oxidation were
prepared following the exemplary method. The starting material used was α-cellulose,
C8002 from Sigma Aldrich. Approx. 5g was used for each sample. Details are summarised
in Table 1.
Table 1 - Modified cellulose samples with different % oxidation
|
Dry mass cellulose /g |
Mole ratio catalysts/reagent relative to glucose units |
Degree of oxidation = % glucose units oxidised, based on titration with NaOH |
|
|
TEMPO |
NaBr |
NaOCl |
% |
# 1 |
4.85 |
0.0075 |
0.16 |
1.36 |
71 |
# 2 |
4.75 |
0.0077 |
0.17 |
1.26 |
68 |
# 3 |
4.81 |
0.0075 |
0.16 |
1.12 |
59 |
# 4 |
4.77 |
0.0076 |
0.17 |
1.01 |
53 |
# 5 |
4.80 |
0.0076 |
0.16 |
0.87 |
46 |
# 6 |
4.75 |
0.0077 |
0.17 |
0.76 |
38 |
# 7 |
4.83 |
0.0075 |
0.16 |
0.62 |
31 |
# 8 |
4.87 |
0.0075 |
0.16 |
0.49 |
25 |
[0072] All eight samples were able to be dispersed in water by sonication for up to 40 minutes.
Those less oxidised gave somewhat turbid suspensions. The more highly oxidised samples
became completely transparent after a relatively short sonication time.
[0073] Aqueous dispersions of up to 2 % (by weight) of modified cellulose are free-flowing
(although more viscous than water). Above this concentration, or in the presence of
electrolytes, the dispersions become thicker, eventually forming gels, which may be
opaque.
Example 1 - Adding surfactant
[0074] Surfactants were added to sonicated dispersions of modified cellulose samples with
differing degrees of oxidation. No extra electrolyte was added. Surprisingly, addition
of small quantities of surfactant to the dispersions yielded clear gels. Amounts of
surfactant given in the table are based on active content. The activity of the nonionic
surfactant was not certain, but is thought to be near to 100%. Surfactants used were
as follows:
Anionic surfactants |
|
% active |
LS |
Sodium lauroyl sarcosinate |
Medialan LD |
31 |
LL |
Sodium lauroyl lactylate |
Pationic 138C |
98 |
CG |
Sodium cocoyl glutamate |
Hostapon KCG |
25 |
PGS |
Disodium coco-glucoside sulfosuccinate |
Eucarol AGE/SS |
45 |
PGC |
Disodium coco-glucoside citrate |
Eucarol AGE/EC |
31 |
SLES1 |
Sodium lauryl ether sulphate (1 EO) |
|
70 |
SLES3 |
Sodium lauryl ether sulphate (3 EO) |
|
70 |
|
|
|
|
Amphoteric surfactant |
|
|
CAA |
Sodium cocoamphoacetate |
Miranol Ultra C32 |
31 |
|
|
|
|
Nonionic surfactant |
|
|
STO |
sorbitan trioleate |
Span 85V Pharma |
≤100 |
[0075] Results are given in Table 2.
Table 2 - Surfactant / modified oxidised cellulose compositions
Modified cellulose biopolymer = 30% oxidised |
Example |
1.1 |
1.2 |
1.3 |
1.4 |
1.5 |
1.6 |
1.7 |
Cell % |
1.3 |
1.3 |
1.3 |
1.3 |
1.3 |
1.3 |
1.3 |
Surfactant % |
0.25 |
0.28 |
≤0.9 |
0.45 |
0.2 |
0.39 |
- |
Surfactant |
CAA |
PGC |
STO |
PGS |
CG |
LL |
- |
Surfactant Type |
Amphoteric |
Anionic |
Nonionic |
Anionic |
Anionic |
Anionic |
None |
|
Thixotropic gel Medium Bubbles trapped Translucent |
Thixotropic gel Soft No bubbles Translucent |
Free-flowing liquid Opaque |
Thixotropic gel Medium Bubbles trapped Translucent |
Thixotropic gel Lumpy Semi-translucent |
Thixotropic gel Medium-evidence of particles Semi-translucent |
Thickened liquid Almost clear |
Modified cellulose biopolymer = 43% oxidised) |
Example |
1.8 |
1.9 |
1.10 |
1.11 |
1.12 |
1.13 |
1.14 |
Cell / % |
1.3 |
1.3 |
1.3 |
1.3 |
1.3 |
1.3 |
1.3 |
Surfactant % |
0.62 |
0.65 |
0.65 |
1.17 |
0.35 |
0.88 |
- |
Surfactant |
CAA |
PGC |
LS |
PGS |
CG |
LL |
- |
Surfactant Type |
Amphoteric |
Anionic |
Anionic |
Anionic |
Anionic |
Anionic |
None |
|
Thixotropic gel Clear gel Firm Traps bubbles for months Some syneresis |
Thixotropic gel Clear gel medium Traps bubbles for months |
Thixotropic gel Clear gel medium Traps bubbles for months |
Thixotropic gel Clear gel Firm Traps bubbles for months Breaks up on shaking / some
syneresis |
Thixotropic gel clear-gel medium Traps bubbles for months Breaks up on shaking / some
syneresis |
Thixotropic gel Semi-translucent gel traps bubbles Breaks up on shaking / evidence
of gel particles |
Thickened liquid |
[0076] Examples 1.3, 1.7 and 1.14 are comparative, as they do not include any anionic or
amphoteric surfactant. Table 2 shows that combination of oxidised, dispersed cellulose
with anionic surfactants and zwitterionic (betaine) surfactants provides gelled material,
while no such gels result in the presence of the nonionic sorbitan surfactant.
Examples 2 and 3- Surfactant and electrolyte concentration
[0077] A series of experiments were carried out in which concentrations of NaCl electrolyte
and two anionic surfactants (SLES 1 EO and SLES 3EO) were altered. Water, oxidised
cellulose dispersion, surfactant solution, and NaCl solution, were added in that order.
The degree of oxidation of the modified cellulose was 28-29% for all these samples.
Finally, pH was adjusted with HCl(aq) and total volume made up with water. The concentration
of oxidised dispersed cellulose was varied between 0.5 and 1.5 wt %; the concentration
of NaCl between 0 and 2 wt % and that of the surfactant between 0 and 10 wt %. Results
for these surfactants are summarised in Tables 3, and 4. SLES 1 EO (as used in detergent
formulations); NaCl; pH adjusted to 6 is shown in Table 3. SLES 3EO (as used in concentrated
laundry); NaCl pH adjusted to 8 is shown in Table 4. Comparative examples are indicated
using N + letter. Examples of inventive compositions are indicated by N + number.
[0078] SLES 1 EO is known to form gels, at relatively low concentrations, in the presence
of electrolytes such as NaCl, but the observed similar behaviour with other surfactants,
for example as described in example 3 below, implies that the effect is due to an
interaction of the oxidised cellulose with the surfactant electrolytes.
[0079] For each surfactant, combinations exist that provide product of soft gel-like consistency
which may be induced to flow by the application of shear stress and which resets on
standing. Addition of high concentrations of surfactant and salt leads to the formation
of gel particles, which may separate, floating or sinking, depending on the inclusion
of air bubbles. The gel formed by addition of NaCl alone appeared opalescent, while
those with the same quantity of NaCl and the anionic surfactants were clear.
Example 4 - Other additives
[0080] A series of samples were made, in which the modified cellulose and surfactant aqueous
compositions were combined with other formulation ingredients.
[0081] A combination of SLES 1 EO (5 % by wt) and dispersed oxidised cellulose (1.3 % by
wt) yields a soft transparent gel, which, on shaking, breaks up and flows, regelling
on standing post disruption. Bubbles, solid beads, encaps or other visual aids added
to the suspension and dispersed by shaking remain suspended in the transparent gel.
Perfumed microcaps and the associated bubbles, formed on shaking, remain suspended
for several months Similarly, beads or encapsulated benefit agents and glitter particles
remain homogeneously suspended for several months.
[0082] Beads, bubbles and glitter particles were suspended in vials containing ca 2 mL of
a soft gel formed by addition of SLES 1 EO to a dispersion of oxidised cellulose (composition:
1.3 % oxidised cellulose; 5 % SLES 1EO). a) plus 114 mg perfume microcapsule suspension;
b) 86 mg perfume microcaps suspension c) plus 125 mg perfume microcaps d) plus 17
mg "Colorona" Glitter Copper powder. Shaking of the loaded gels renders them flowable
and regelling occurs reasonably rapidly post disturbance. Gels are smooth to the touch
with no feeling of "graininess", spread easily on the skin and may be extruded smoothly
through an orifice or pumped.
[0083] Addition of hydrophobic oils such as liquid paraffin or silicon oil DC200, 50 cS
viscosity (20 %) to mixtures of dispersed oxidised cellulose (0.9 %) and SLES 1 EO
(5.7 %) followed by homogenisation using a handheld Ultraturrax device, leads to the
formation of white emulsions. Addition of a small amount of NaCl converts the silicon
oil emulsion to a firm gel. (By comparison, a mixture of silicon oil, water and SLES
in similar ratios rapidly separates yielding a clear aqueous solution topped by the
creamed emulsified oil).
1. A structured aqueous detergent composition comprising modified cellulose and surfactant
characterised in that the composition comprises:
a) 0.2 to 10 wt %, preferably 0.4 to 7 wt%, anionic surfactant or zwitterionic surfactant
or mixtures thereof,
b) 0.5 to 5 wt %, preferably 1 to 2 wt%, dispersed modified cellulose biopolymer,
wherein the modification consists of the cellulose having its C6 primary alcohols
oxidised to carboxyl moieties (acid/COOH-) on 10 to 70% of the glucose units and substantially
all the remainder of the C6 positions occupied by unmodified primary alcohols,
c) 0 to 10 wt % non-surfactant electrolyte;
d) 0 to 15 wt% other conventional detergent composition additives
e) water
2. A composition according to claim 1 further comprising perfume, perfume encapsulates,
small beads, free emulsions air bubbles and combinations thereof suspended in the
composition.
3. A composition according to claim 1 having more than 1 wt% modified biopolymer structurant
and more than 1wt % surfactant system.
4. A composition according to claim 1 in which the total amount of surfactant, including
any co-surfactant, and/or any emulsifier, in the detergent compositions is from 0.2
to 10wt%, preferably from 0.4 to 7 wt%, more preferably from 0.5 to 5% based on the
total weight of the composition.
5. A composition according to claim 1 comprising an anionic surfactant selected from
the group comprising sodium lauroyl sarcosinate, sodium lauroyl lactylate, sodium
cocoyl glutamate, disodium alkylpolyglucose sulfosuccinate / citrate, sodium lauryl
ether sulphate (1-3 EO).
6. A composition according to claim 1 comprising an amphoteric surfactant which is sodium
cocoamphoacetate.
7. A composition according to claim 1 in which the non-surfactant electrolyte is sodium
chloride in an amount of from 1 to 10 wt%
8. A composition according to claim 1 In which the other additives are included in amount
of up to 15 wt% for enhancing performance and/or consumer acceptability the other
additives being selected from fragrance, dyes and pigments, pH adjusting agents, pearlescers
or opacifiers, viscosity modifiers, preservatives, natural hair nutrients, such as
botanicals, fruit extracts, sugar derivatives and amino acids.
9. A process to manufacture a structured aqueous detergent composition according to claim
1, the process comprising the steps of:
(i) dispersing 0.5 to 5 wt % modified cellulose biopolymer in water under high shear
to hydrate it, the wherein the modification consists of the cellulose having its C6
primary alcohols oxidised to carboxyl moieties (acid/COOH-) on 10 to 70% of the glucose
units and substantially all the remainder of the C6 positions occupied by unmodified
primary alcohols,
(ii) adding 0.2 to 10 wt % of a surfactant system consisting of anionic or zwitterionic
surfactant, or mixtures of such surfactants, to this aqueous dispersion,
(iii) optionally also adding 0 to 10 wt % non-surfactant electrolyte,
(iv) optionally mixing in up to 15 wt% other conventional detergent additives to make
a structured aqueous detergent composition.
10. A process according to claim 9 in which the oxidation is catalysed using TEMPO.
11. A process according to claim 9 or 10 in which the non-surfactant electrolyte has a
monovalent cation.
1. Strukturierte wässrige Waschzusammensetzung,
die modifizierte Cellulose und Tensid aufweist,
dadurch gekennzeichnet, dass die Zusammensetzung Folgendes aufweist:
a) 0,2 bis 10 Gew.-%, vorzugsweise 0,4 bis 7 Gew.-% anionisches Tensid oder zwitterionisches
Tensid oder Gemische davon,
b) 0,5 bis 5 Gew.-%, vorzugsweise 1 bis 2 Gew.-% dispergiertes modifiziertes Cellulose-Biopolymer,
wobei die Modifizierung darin besteht, dass bei der Cellulose primäre C6-Alkohole an 10 bis 70 % der Glucose-Einheiten zu Carboxyl-Einheiten (Säure/COOH-)
oxidiert sind und im Wesentlichen der gesamte Rest der C6-Positionen von nicht-modifizierten primären Alkoholen eingenommen wird,
c) 0 bis 10 Gew.-% tensidfreier Elektrolyt,
d) 0 bis 15 Gew.-% andere herkömmliche Zusätze für Waschzusammensetzungen,
e) Wasser.
2. Zusammensetzung nach Anspruch 1,
die ferner Duftstoffe, verkapselte Duftstoffe, kleine Kügelchen, ungebundene Emulsionen,
Luftbläschen und Kombinationen davon aufweist, die in der Zusammensetzung suspendiert
sind.
3. Zusammensetzung nach Anspruch 1,
die mehr als 1 Gew.-% eines strukturbildenden Mittels in Form eines modifizierten
Biopolymers und mehr als 1 Gew.-% Tensidsystem aufweist.
4. Zusammensetzung nach Anspruch 1,
wobei die gesamte Tensidmenge, einschließlich irgendeines Cotensids und/oder irgendeines
Emulgators, in den Waschzusammensetzungen 0,2 bis 10 Gew.-%, vorzugsweise 0,4 bis
7 Gew.-%, stärker bevorzugt 0,5 bis 5 % ausmacht, und zwar auf das Gesamtgewicht der
Zusammensetzung bezogen.
5. Zusammensetzung nach Anspruch 1,
die ein anionisches Tensid aufweist, das aus der Gruppe ausgewählt ist, die Natriumlauroylsarcosinat,
Natriumlauroyllactylat, Natriumcocoylglutamat, Dinatriumalkylpolyglucosesulfosuccinat/citrat,
Natriumlaurylethersulfat (1-3 EO) umfasst.
6. Zusammensetzung nach Anspruch 1,
die ein amphoteres Tensid aufweist, das Natriumcocosamphoacetat ist.
7. Zusammensetzung nach Anspruch 1,
wobei der tensidfreie Elektrolyt Natriumchlorid in einer Menge von 1 bis 10 Gew.-%
ist.
8. Zusammensetzung nach Anspruch 1,
wobei die anderen Zusätze in einer Menge von bis zu 15 Gew.-% enthalten sind, um die
Leistung und/oder die Akzeptanz durch den Verbraucher zu verbessern, wobei die anderen
Zusätze aus Duftstoffen, Farbstoffen und Pigmenten, den pH-Wert regelnden Mitteln,
Perlmutteffektmitteln oder Trübungsmitteln, Viskositätsverbesserern, Konservierungsmitteln,
natürlichen Haarnährstoffen, wie botanische Stoffe, Fruchtextrakte, Zuckerderivate
und Aminosäuren, ausgewählt sind.
9. Verfahren zum Herstellen einer strukturierten wässrigen Waschzusammensetzung nach
Anspruch 1,
wobei das Verfahren die folgenden Schritte aufweist:
(i) Dispergieren von 0,5 bis 5 Gew.-% modifiziertem Cellulose-Bipolymer in Wasser
unter einer starken Scherung, um es zu hydratisieren, wobei die Modifikation darin
besteht, dass bei der Cellulose primäre C6-Alkohole an 10 bis 70 % der Glucose-Einheiten zu Carboxyl-Einheiten (Säure/COOH-)
oxidiert sind und im Wesentlichen der gesamte Rest der C6-Positionen von nicht-modifizierten primären Alkoholen eingenommen wird,
(ii) Zugeben von 0,2 bis 10 Gew.-% eines Tensidsystems, das aus anionischem oder zwitterionischem
Tensid oder Gemischen solcher Tenside besteht, zu dieser wässrigen Dispersion,
(iii) gegebenenfalls auch Zugeben von 0 bis 10 Gew.-% tensidfreiem Elektrolyt,
(iv) gegebenenfalls Einmischen von bis zu 15 Gew.-% anderer herkömmlicher Waschzusätze,
um eine strukturierte wässrige Waschzusammensetzung herzustellen.
10. Verfahren nach Anspruch 9,
wobei die Oxidation unter Verwendung von TEMPO katalysiert wird.
11. Verfahren nach Anspruch 9 oder 10,
wobei der tensidfreie Elektrolyt ein einwertiges Kation aufweist.
1. Composition détergente aqueuse structurée comprenant de la cellulose modifiée et un
tensio-actif,
caractérisée en ce que la composition comprend :
a) de 0,2 à 10 % en poids, de préférence de 0,4 à 7 % en poids, d'un tensioactif anionique
ou d'un tensioactif zwittérionique ou d'un mélange de ceux-ci,
b) de 0, 5 à 5 %, de préférence de 1 à 2 % en poids, d'un biopolymère de cellulose
modifiée dispersé, la modification consistant en ce que la cellulose a ses alcools primaires en C6 oxydés en groupements carboxyle (acide/COOH-)
sur 10 à 70 % des motifs de glucose et que sensiblement toutes les autres positions
en C6 sont occupées par des alcools primaires non modifiés,
c) de 0 à 10 % en poids d'un électrolyte non tensioactif,
d) de 0 à 15 % en poids d'autres additifs de compositions détergentes classiques,
e) de l'eau.
2. Composition selon la revendication 1, comprenant en outre un parfum, des agents d'encapsulation
de parfum, des petites billes, des émulsions, des bulles d'air et des mélanges de
ceux-ci suspendus dans la composition.
3. Composition selon la revendication 1, ayant plus de 1 % en poids d'un structurant
biopolymère modifié et plus de 1 % en poids d'un système tensioactif.
4. Composition selon la revendication 1, dans laquelle la quantité totale de tensioactif,
y compris tout co-tensioactif, et/ou tout émulsifiant, dans la composition détergente
est de 0,2 à 10 % en poids, de préférence de 0,4 à 7 % en poids, plus préférablement
de 0,5 à 5 % en poids, par rapport au poids total de la composition.
5. Composition selon la revendication 1, comprenant en outre un tensioactif anionique
choisi dans le groupe comprenant le lauroylsarcosinate de sodium, le lauroyllactylate
de sodium, le cocoylglutamate de sodium, le citrate/ sulfosuccinate d'alkylpolyglucose
disodique, le sulfate d'éther laurylique de sodium (1 à 3 OE).
6. Composition selon la revendication 1, comprenant un tensioactif amphotère qui est
le cocoamphoacétate de sodium.
7. Composition selon la revendication 1, dans laquelle l'électrolyte non tensioactif
est le chlorure de sodium en une quantité de 1 à 10 % en poids.
8. Composition selon la revendication 1, dans laquelle les autres additifs sont inclus
en une quantité allant jusqu'à 15 % en poids pour améliorer la performance et/ou l'acceptabilité
par le consommateur, les autres additifs étant choisis parmi les parfums, les colorants
et les pigments, les ajusteurs de pH, les agents nacrants ou les opacifiants, les
modificateurs de viscosité, les conservateurs, les nutriments capillaires naturels,
tels que les produits botaniques, les extraits de fruit, les dérivés du sucre et les
acides aminés.
9. Procédé de préparation d'une composition détergente aqueuse structurée selon la revendication
1, le procédé comprenant les étapes de :
(i) dispersion de 0,5 à 5 % en poids d'un biopolymère de cellulose modifiée dans de
l'eau avec un cisaillement rapide pour l'hydrater, la modification consistant en ce
que la cellulose ait ses alcools primaires en C6 oxydés en groupements carboxyle (acide/COOH-)
sur 10 à 70 % des motifs de glucose et que sensiblement toutes les autres positions
en C6 soient occupées par des alcools primaires non modifiés,
(ii) ajout de 0,2 à 10 % en poids d'un système tensioactif constitué d'un tensioactif
anionique ou zwittérionique, ou de mélanges de ces tensioactifs, à la dispersion aqueuse,
(iii) ajout également facultatif de 0 à 10 % en poids d'un électrolyte non tensioactif,
(iv) incorporation facultative jusqu'à 15 % en poids d'autres additifs détergents
classiques pour donner une composition détergente aqueuse structurée.
10. Procédé selon la revendication 9, dans lequel l'oxydation est catalysée en utilisant
du TEMPO.
11. Procédé selon la revendication 9 ou 10, dans lequel l'électrolyte non tensioactif
a un cation monovalent.